1. Field of the Invention
The present invention relates to an LED. In particular, this invention relates to an SMD diode holding structure and a package thereof that improves the brightness and can be easily manufactured.
2. Description of the Related Art
FIG. 1 shows the SMD (surface mount device) diode packaging structure of the prior art. On two metal holders 11, a plastic housing 12 is molded and has a concave portion in the interior of the plastic housing 12. An LED chip 13 is located on one of the metal holders 11 in the plastic housing 12. The LED chip 13 and the two metal holders 11 are connected with two conductive wires 14. In order to prevent the LED chip 13 from being damaged by static electricity, another metal holder 11 is connected with an anti-ESD chip 15. The anti-ESD chip 15 is connected with the metal holder 11 via another conductive wire 14′. Finally, the plastic housing is covered with epoxy resin 16. By exerting a voltage on the two metal holders, the LED chip 13 emits light and is protected by the anti-ESD chip 15.
However, in the SMD diode packaging structure of the prior art, due to the heights of the LED chip 13 and the anti-ESD chip 15, light emitted from the LED chip 13 has a high reflective rate between the wall in the plastic housing 12 and the metal holder 11. Moreover, when light passes through the anti-ESD chip 15, light is easily affected by the height of the anti-ESD chip 15, thereby light-shielding and light-absorbing effects are generated. The reflective rate is bad and the brightness of the LED is not uniform.
In order to solve the problem, Taiwan patent M261831, granted on 11 Apr. 2005, discloses an LED anti-ESD packaging structure. The LED anti-ESD packaging structure includes a holder 21 having a concave portion 211 on one surface of the holder 21, a protective element 22 fastened in the concave portion 211 via a pasting material 23 and connected with the holder 21 via a conductive wire 24, a molding element 25 packages the concave portion 211 and forms an arched concave cup 251 on a second surface that is disposed opposite to the concave portion, and an LED chip 26 that is fastened into the arched concave cup 251 via a pasting material 23′ and connected with the holder 21 via two conductive wires 24′. When a voltage is exerted on the metal holders 21, the LED chip 26 emits light. By respectively fastening the protective element 22 and the LED chip 26 onto the holders 21, the light-shielding and light-absorbing effects caused by the protective element 22 are avoided.
The protective element 22 in the described LED anti-ESD packaging structure is fastened in the concave portion 211 via conductive silver glue. Next, the protective element 22 is connected with the conductive wire 24 and is fastened in the concave portion 211 of the holding structure by a pasting material 23. The molding element 25 packages the concave portion 211, the protective element 22, and the pasting material 23 by using an injection method or a molding method, thereby forming the arched concave cup 251. Finally, the holder 21 located on the other surface is fastened with the LED chip 26 and is connected with the conductive wires 24′.
However, in the manufacturing process, there are the following drawbacks:
1. The concave portion 211 is formed on the holder 21 via a punching method or an etching method. When the conductive wire 24 is wired, the holder 21 vibrates and the pulling force is unstable. The unstable force could cause the microdamage of LED/anti-ESD chips structure.
The product is unreliable.
2. The concave portion 211 has a concave-cup shape (as shown in FIG. 2). If too much of the silver glue that is used for fastening the protective element is applied, the silver glue will overflow the wall of the concave portion 211 and become attached to the side of the protective element 22. Electricity-leakages occur and a short circuit may ensue.
3. Whatever kind of material the molding element 25 is made of, the molding element 25 needs to reach a high temperature and a melting status to package the holders 21, the concave portion 211, the protective element 22 and the pasting material 23. In the packaging process, the pasting material 23 will deteriorate due to the high temperatures.